Observation of exciton-exciton scattering inCu2O by time-resolved photomodulation spectroscopy

Transient photomodulation techniques with picosecond laser pulses have been applied to make contact with excitonic scattering through several nP transitions of the yellow exciton series in ${\mathrm{Cu}}_2$O. We show first how this experimental approach can be generally useful in the dynamical study of collisionally broadened free-exciton resonances, and then argue that the observed time-dependent spectra give direct information about the energy-dependent character of nP-1S exciton scattering events in ${\mathrm{Cu}}_2$O under conditions of weak photoexcitation considered here.